Spectacle lens and manufacturing method therefor

ABSTRACT

An eyeglass having a prescription face optimized considering the individual wearing conditions, and a method for manufacturing the eyeglass. Information including the prescribed values including data relate to the VR value of each eyeglass wearer necessary to design and manufacture the eyeglass are transmitted through a terminal installed in an optician (on the orderer&#39;s side) to a host computer installed in an eyeglass manufacturer (on the manufacturer&#39;s side). The information is processed by the host computer to determine the eyeglass shape optimized on the basis of an optical model under simulated wearing conditions and to determine the manufacturing conditions. Thus, an eyeglass is manufactured by a numerical controlled machine and an edger and is delivered to the orderer&#39;s side.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a spectacle lens, which is designed andmanufactured taking into consideration the distance between the centerof rotation of the eye and a spectacle lens of an individual spectacleswearer, and a manufacturing method therefor.

2. Description of the Related Art

Despite the fact that spectacle lenses comprises single vision lensesand multifocal lenses (including progressive-power lenses) withdifferent optical characteristics, they are generally designed on thebasis of certain average utilization conditions. An example in whichindividual utilization conditions are taken into consideration is themethod disclosed in Japanese Patent Application Laid-open No. 6-18823,in which there is proposed a progressive-power lens designed inconsideration of individual utilization conditions, and there isdisclosed the use of an aspheric surface, which is not accompanied bypoint symmetry axial symmetry in a prescription surface. The term“utilization conditions” as used here refers to the distance between theback surface of a spectacle lens (the surface of the eye side) and thevertex of the cornea, the tilt of the frame, and so forth, and anattempt is made to optimize a prescription surface by using these datain lens design.

However, the technique disclosed in the above-mentioned publication hasan object to optimize a progressive-power lens comprising a distanceportion, a near portion, and an intermediate portion, and having aprescription surface for both far and near vision use, and inparticular, takes into consideration the importance of utilizationconditions in the case of a spectacle lens, like a progressive-powerlens, having a prescription, which supplements the accommodative powerin near vision for presbyopia. This is because a progressive-power lensrequires particularly accurate adjustment of s determining theconditions of a corrective prescription, is deemed particularlynecessary. Therefore, the disclosure in the publication only emphasizesthe accurateness of a near use prescription, and does not addressoverall wearing conditions for lenses such as spherical design lenses,aspherical single vision lenses, and bifocal lenses.

The present invention was devised based on the above-mentionedcircumstances, and has as an object to provide a spectacle lens and amanufacturing method thereof, having a prescription surface which hasbeen further optimized by reviewing the wearing conditions for allspectacle lenses, which was not paid much attention to in the past, andby taking into consideration individual wearing conditions.

SUMMARY OF THE INVENTION

As a means for solving the above-mentioned problems, a first inventionis a spectacle lens characterized in that a spectacle lens is designedby using a value determined by either measuring or specifying for anindividual spectacles wearer the value of the distance VR from areference point on the back surface of a spectacle lens to the center ofrotation of the eye, which adds together the value of the distance VCfrom a reference point of the back surface of a spectacle lens to thevertex of the cornea of the eye of the spectacles wearer at spectaclelenses wearing time, which is one of the required data in spectacle lensdesign, and the distance CR from the above-mentioned vertex of thecornea to the center of rotation of the eye, and manufacturing aspectacle lens based on this design specification.

A second invention is a spectacle lens related to the first invention,characterized in that the value of the distance CR from theabove-mentioned vertex of the cornea to the center of rotation of theeye utilizes a value obtained based on measurement data obtained bymeasuring the axial length of the eye CO of a spectacles wearer.

A third invention is a spectacle lens related to either the firstinvention or the second invention, characterized in that theabove-mentioned center of rotation of the eye is determined for distancevision, near vision, specified distance vision, and combination thereof,respectively, and is either selected and used on the basis of lensoptical characteristics, or is used for appropriate viewing areas of aspectacle lens, respectively.

A fourth invention is a spectacle lens characterized in that it isprocessed by obtaining an optimized lens form based on an optical modelof wearing conditions simulated in accordance with design and/orprocessing condition data information selected as needed from amonginformation comprising a prescription value, which comprises spectaclelens information, spectacle frame information, and data related to theindividual VR value of a spectacles wearer, layout information, andprocess specification information.

A fifth invention is a spectacle lens related to the fourth invention,characterized in that an amount of inset for near vision is determinedbased on the above-mentioned VR value.

A sixth invention is a spectacle lens related to the fourth invention,characterized in that the base curve of a convex surface is determinedbased on the above-mentioned VR value.

A seventh invention is a spectacle lens related to the fourth invention,characterized in that power error correction for a pre-set referenceprescription surface is performed based on the above-mentioned VR value.

An eighth invention is a spectacle lens manufacturing method, wherein aterminal apparatus, which is installed at a spectacle lens orderingparty, and an information processing system, which is installed at aspectacle lens processing party, and is connected by atelecommunications line to the above-mentioned terminal apparatus areprovided for designing and manufacturing a spectacle lens based oninformation sent to the above-mentioned information processing systemvia the above-mentioned ordering party terminal apparatus; thisspectacle lens manufacturing method comprising the steps of:

sending to the above-mentioned information processing system via theabove-mentioned terminal apparatus design and/or processing conditiondata information selected as needed from among information comprising aprescription value, which comprises spectacle lens information,spectacle frame information, and data related to the VR value of eachspectacles wearer, layout information, and process specificationinformation; and

obtaining an optimized lens form based on an optical model of wearingconditions simulated by the above-mentioned information processingsystem, determining processing conditions, and manufacturing a spectaclelens.

A ninth invention is a spectacle lens manufacturing method, wherein, aterminal apparatus, which is installed at a spectacle lens orderingparty, and an information processing system, which is installed at aspectacle lens processing party, and is connected by atelecommunications line to the above-mentioned terminal apparatus areprovided for designing and manufacturing a spectacle lens based oninformation sent to the above-mentioned information processing systemvia the above-mentioned ordering party terminal apparatus, thisspectacle lens manufacturing method comprising the steps of:

sending to the above-mentioned information processing system via theabove-mentioned terminal apparatus design and/or processing conditiondata information selected as needed from among information comprising aprescription value, which comprises spectacle lens information,spectacle frame information, and data related to the VR value of eachspectacles wearer, layout information, and process specificationinformation:

determining an optimized lens form based on an optical model of wearingconditions simulated by the above-mentioned information processingsystem;

also determining a standardized lens form by the above-mentionedinformation processing system using a standardized VR value in place ofsaid VR value obtained for each spectacles wearer, while using otherdesign and/or processing condition data sent via the above-mentionedterminal,

comparing the optical characteristics of the above-mentioned optimizedlens form against the optical characteristics of the above-mentionedstandardized lens form, and based on the results of the comparisonthereof, selecting either one of the above-mentioned lens forms,determining processing conditions of this selected lens form, andmanufacturing a spectacle lens.

A tenth invention is a spectacle lens manufacturing method wherein, aterminal apparatus, which is installed at a spectacle lens orderingparty, and an information processing system, which is installed at aspectacle lens processing party, and is connected by atelecommunications line to the above-mentioned terminal apparatus areprovided for designing and manufacturing a spectacle lens based oninformation sent to the above-mentioned information processing systemvia the above-mentioned ordering party terminal apparatus, thisspectacle lens manufacturing method comprising the steps of:

inputting via the above-mentioned terminal apparatus design and/orprocessing condition data information selected as needed from amonginformation comprising a prescription value, which comprises spectaclelens information, spectacle frame information, and data related to theVR value of a spectacles wearer, layout information, and processspecification information; and

obtaining an optimized lens form based on an optical model of wearingconditions simulated on the basis of the inputted information thereof,determining processing conditions, and manufacturing a spectacle lens.

The present invention makes it possible to achieve a higher performancespectacle lens by designing a spectacle lens using a value determinedfor each individual spectacles wearer, as a value of distance VR from areference point on the back surface of a spectacle lens to the center ofrotation of the eye when the spectacle lenses is worn, which is one ofthe necessary data in the lens design, and manufacturing the lens basedon the design specifications thus established.

Conventional thinking holds that it is sufficient to use a standardvalue as a VR value, and that the effects that individual differences ofa VR value have on lens performance are practically negligible. That is,as indicated in the above-mentioned Japanese Patent ApplicationLaid-open No. H6-018823, with the prior art, a spectacle lens has beendesigned and manufactured using a standard value as the distance fromthe center of rotation of the eye to the vertex of the cornea. However,the fact is that although a VR value determined on the basis of thisstandard distance is known to be a value that differs from individual toindividual, it has not been well known or accurately verified whateffect this difference has on optical effects, that is, on design of thespectacle lenses. There are a variety of design methods for an opticalsurface of a spectacle lens, and the main concern was optimization ofdesign thereof, while it was out of consideration to verify or simulatethe effect of a VR value for each design. Further, quite naturally,sufficient study has not been done on how this value should be fed backto the design and manufacture processes.

The inventors investigated the differences in VR values betweenindividuals, and conducted research on this subject using a simulationmethod such as the ray tracing method recently developed. They finallyfound out that differences in VR values between individuals areunexpectedly large, and the effects of these differences on lensperformance are also greater than expected. Based on the results of thisresearch, lenses of common basic specifications were actually designedand manufactured in two types, that is, lenses for which differences inVR values between individuals were taken into consideration, and thosefor which they were not, and their performance were compared. Theresults the inventors obtained greatly exceeded their expectations.

That is, it was ascertained that there was large difference in opticalperformance of a spectacle lens in a case where a spectacle lensdesigned and manufactured based on a standard VR value was used for anindividual having a different VR value from the standard VR value, andsuch difference reached an amount requiring correction. Specifically,there are effects related to optical layout related to aberration of asingle-focus lens, the positioning of the segment height when therefracting power at the vertex of the distance portion in bifocal lensesis different between the right and left lenses, an amount of inset ofthe near portion in progressive-power lenses, height of the near portionand so on.

Here, the value of the sum of a value of the distance VC from areference point on the back surface of a spectacle lens to the vertex ofthe cornea of the eye of the spectacles wearer as found when spectaclelenses are being worn by the wearer, and a value of the distance CR fromthis vertex of the cornea to the center of rotation of the eye can beused as the VR value.

For the present invention, the most important factor is the CR value,and because a CR value will differ physiologically from individual toindividual, it is desirable that a CR value be accurately calculated bymeasurement. However, according to circumstances, individual CR valueswill not be necessary for all the cases. For example, it is alsopossible that CR values are classified into 2 to 5 groups, a valuerepresenting the respective groups is set, and this value is used as aCR value for the group. In the present invention, values as designatedby an ordering side, including measured values in the broad sense areused as the CR values in lens design.

As a method for measuring a CR value, for example, it is possible to usethe eye rotation point measuring apparatus proposed by G. A. Fry and W.W. Hill and described in an article titled “THE CENTER OF ROTATION OFTHE EYE” in the AMERICAN JOURNAL OF OPTOMETRY and ARCHIVES of AMERICANACADEMY OF OPTOMETRY (vol. 39, published November 1962). Further, thereis also a method, by which a CR value is found by computing from thepoint of intersection of lines of sight of different directions.

Further, as a simple and practical method, there is a method ofutilizing a widely used apparatus for measuring the axial length of theeye. That is, it is a method, which measures the axial length of theeye, wherefrom finds the central point of rotation of the eye bycalculation. For example, in this method, general statistical data ofthe relative position of the rotating point of the eye to a previouslymeasured axial length are used. For example, if it is supposed that, asaverage data, the axial length of the eye is 24 millimeters, and thedistance from the vertex of the cornea to the central point of rotation(CR) is 13 millimeters, 13/24=0.54 constitutes the utilization ratio.Therefore, in the case of a person, for whom the axial length of the eyeis detected as 27 millimeters, using this relative position coefficient0.54, it is supposed that the value of this person's CR is 27millimeters×0.54=14.6 millimeters. In addition thereto, various methodscan be used to find the correlation between the point of rotation of theeye and the axial length of the eye for establishing the point ofrotation of the eye.

There are various apparatuses for measuring the axial length of the eye,including, for example, ultrasonic sound measuring apparatuses and sightline direction detecting apparatus. Further, the location of the centralpoint of rotation of the eye is not a fixed point in the eye, but ratheris believed to change slightly in accordance with the direction ordistance one is trying to view, as when viewing at a distance, and whenviewing up close. Therefore, preferably, it is desirable to carry outprocessing on data differently according to the properties of the lensbeing designed, before using same in a design. For example, in the caseof a progressive-power lens, different values of the location of centralpoint of rotation as found in distance vision and in near vision areused respectively, for the distance vision region and the near visionregion; in the case of a single vision lens for distance vision, a valueof the location of central point of rotation as found in distance visionis used; and in the case of single vision lens for presbyopia, a valueof the location of central point of rotation as found in near vision isused. Further, it is also possible to treat measurement data from onedirection as basic data, apply corrective values thereto, and use thismeasurement data in various ways.

Further, there is no special measuring apparatus for determining a VCvalue like there is for a CR value, but it is important to accuratelydetermine a VC value. But this value differs from a CR value, and is nota purely physiological value, and since there is also a correlationbetween a VC value and the wearing condition of a frame, this value isadjusted by the side that transmits a prescription value (anoptometrist, optician, or the like). Since there are also cases in whicha VC value can be adjusted to a certain prescribed value (for example, avalue determined by an optician), in the present invention, VC valuesare treated, in the broad sense, as designated values.

In this manner, according to the present invention, spectacle lensdesign is performed for the right and left eyes of each individual byusing a VC value for the distance from a reference point on the backsurface of a spectacle lens to the vertex of the cornea of the eye of aspectacles wearer, and a CR value for the distance from the vertex ofthe cornea to the center of rotation of the eye, but it is alsoimportant to compare a spectacle lens designed according to the presentinvention against a standard spectacle lens designed and manufactured byan existing design technique, and to give comparative data as to howdifferent they are.

That is, because lenses, which were designed as spectacle lenses using aVC value and a CR value of the right and left eyes of each individual,respectively, are individually designed products that are manufacturedone product at a time, manufacturing costs are higher than for astandardized product (standard product) that is manufactured in volume.

However, there are cases when even lenses, which were designed asspectacle lenses using a VC value and a CR value of the right and lefteyes of each individual, respectively, become identical to a standardproduct, and there are cases when even if there is a difference, it isonly a slight difference. In such cases, it will be disadvantageous forthe end user to select and purchase a relatively expensive product thatis manufactured one product at a time. Naturally, it is clear that theperformance of the spectacle lenses by a design based on individual byindividual information would not differ greatly even when compared to astandard product. In other words, it is believed the user would feellike the newly prepared spectacles do not differ much compared to thespectacles he had used up until now, and would feel displeased at havingselected and purchased a relatively expensive product.

Thus, it is necessary to clarify the difference in opticalcharacteristics (astigmatism, average power, power error, and so forth)between a standard product and a spectacle lens by a design based onindividual by individual information when trying to make a selectionprior to ordering a spectacle lens.

Thus, when ordering information, such as a prescription value, whichcomprises spectacle lens information, spectacle frame information, anddata related to a VR value of each spectacles wearer from a spectaclesstore, layout information, and process specification information is sentto the information processing system of the spectacles processor sidefrom the terminal apparatus of the spectacles store side, it isnecessary to compute in the information processing system of theprocessor side the difference between a standardized product andspectacle lenses by a design based on individual by individualinformation, which was either ordered, or inquired about, to send areply to the terminal apparatus of the spectacles store side, and todisplay optical characteristic information, such as an astigmatismdistribution chart, and an average power distribution chart.

By providing comparative information in this manner, it becomes possibleto cancel the selection of an individually designed product and purchasea standardized product when there is not much difference between anindividually designed product and a standardized product.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a manufacturing method of a spectaclelens related to an aspect of the embodiment of the present invention;

FIG. 2 is a schematic diagram of an ordering screen;

FIG. 3 is a flowchart of a manufacturing process of a spectacle lens;

FIG. 4 is a schematic diagram of an optical model of spectacles wearing;

FIG. 5 is a diagram showing optical data of a prescription lens with a27 mm VR value, which was manufactured using a spectacle lensmanufacturing method related to an aspect of the embodiment;

FIG. 6 is a diagram showing performance data of a case in which a personwith a 27 mm VR value wore a prescription lens with a 27 mm VR value(Refer to FIG. 5);

FIG. 7 is a diagram showing performance data of a case in which a personwith a 33 mm VR value wore a prescription lens with a 27 mm VR value(Refer to FIG. 5);

FIG. 8 is a diagram showing optical data of a prescription lens with a33 mm VR value;

FIG. 9 is a diagram showing performance data of a case in which a personwith a 33 mm VR value wore a prescription lens with a 33 mm VR value(Refer to FIG. 8);

FIG. 10 is a diagram showing optical data of a prescription lens with a27 mm VR value in a case in which power is +4.00 (D):

FIG. 11 is a diagram showing performance data of a case in which aperson with a 27 mm VR value wore a prescription lens with a 27 mm VRvalue (Refer to FIG. 10);

FIG. 12 is a diagram showing performance data of a case in which aperson with a 33 mm VR value wore a prescription lens with a 27 mm VRvalue (Refer to FIG. 10);

FIG. 13 is a diagram showing optical data of a prescription lens with a33 mm VR value in a case in which power is +4.00 (D);

FIG. 14 is a diagram showing performance data of a case in which aperson with a 33 mm VR value wore a prescription lens with a 33 mm VRvalue (Refer to FIG. 13);

FIG. 15 is a table for determining and showing power errors for variouscombinations of convex surface curve (base curve) values and lens powervalues in a case in which there is a single vision lens, and the VRvalue is set at 27 mm;

FIG. 16 is a graph for showing the relationships indicated in FIG. 15 aspower error contour lines:

FIG. 17 is a table for determining and showing power errors for variouscombinations of convex surface curve (base curve) values and lens powervalues in a case in which there is a single vision lens, and the VRvalue is set at 33 mm;

FIG. 18 is a graph for showing the relationships indicated in FIG. 17 aspower error contour lines;

FIG. 19 is a flowchart showing design procedures for a progressive-powerlens;

FIGS. 20-1, 20-2, and 20-3 are diagrams showing the distribution ofsurface astigmatism and surface average power of progressive refractingsurfaces in design examples of a progressive refracting surface of aprogressive-power lens with addition 2.00 D when, as a condition,VR=27.0 mm is provided as a standard value;

FIGS. 21-1, 21-2, and 21-3 are diagrams showing the distribution ofsurface astigmatism and surface average power of progressive refractingsurfaces in design examples of when only the VR value of the designexamples of FIG. 20 is treated as a value that is larger than thestandard value, and is given as VR=33.0 mm;

FIGS. 22-1, 22-2, and 22-3 are diagrams showing the distribution ofsurface astigmatism and surface average power of progressive refractingsurfaces in design examples when only the VR value of the designexamples of FIG. 20 is treated as a value that is smaller than thestandard value, and is given as VR=20.0 mm;

FIG. 23 is a diagram showing the results of calculating as specificnumerals an inset INSET of a near portion provided to the respectivedetermined progressive retracting surfaces shown in FIGS. 20, 21, and22:

FIG. 24 is a diagram illustrating the divergence of the visual linebetween INSET0 and INSET1:

FIG. 25 is a schematic diagram of a progressive-power lens; and

FIG. 26 is a schematic diagram of a bifocal lens.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Aspects of the embodiment of the present invention will be explainedhereinbelow based on the figures. FIG. 1 is a schematic diagram of amanufacturing method of a spectacle lens related to an aspect of theembodiment of the present invention, FIG. 2 is a schematic diagram of anordering screen, FIG. 3 is a flowchart of a manufacturing process of aspectacle lens, and FIG. 4 is a schematic diagram of an optical model ofspectacles wearing.

In FIG. 1, Reference Numeral 1 is a spectacles store (ordering party)and Reference Numeral 2 is a spectacles processor (processing party).The spectacle lens manufacturing method of this aspect of the embodimentis such that a spectacle lens 3 is designed and manufactured based oninformation sent via a terminal apparatus installed at the spectaclesstore (ordering party) 1 to an information processing system installedat the processor (processing party) 2.

That is, via the above-mentioned terminal apparatus there is sent to theabove-mentioned information processing system design and/or processingcondition data information selected as needed from among informationcomprising a prescription value, which comprises spectacle lensinformation, spectacle frame information, and data related to theindividual VR value of a spectacles wearer, layout information, andprocess specification information. The above-mentioned informationprocessing system determines processing conditions by processing theinformation thereof, and obtains an optimized lens form based on anoptical model of simulated wearing conditions, and a spectacle lens ismanufactured. These processes will be explained in detail hereinbelow.

(Preparation of Prescription Data and Lens Data)

The preparation of prescription data and lens data for a spectacleswearer is performed at a spectacles store. Firstly, to determine a VRvalue for an individual (one of the prescription data), which is acharacteristic of this aspect of the embodiment, a CR value of the righteye and left eye of each customer is measured, respectively, using a CRmeasuring apparatus. However, in this aspect of the embodiment, as asimplified method, first, the axial length of the eye of the left andright eyes, respectively, are measured using a popular commercial axiallength measuring apparatus, and next, using a comparison coefficient ofthe relative location of the center of rotation of the eye (verticaldirection) relative to the axial length of the eye, a CR value iscomputed via an operation, and this is used as the CR value for the lefteye and right eye.

Next, the prescription is confirmed once again using either optometrydata (spherical power, cylindrical power, cylinder axis, prismaticpower, prism base setting, addition, distance PD, near PD, and so forth)from a customer's optometrist, or, as necessary, based on the optometrydata thereof, using optometry equipment installed at a spectacles store.Then, lens data in prepared by making determinations based oninteraction with the customer as to lens processing specification data,comprising the type of lens (single vision (spherical, aspherical),multifocal (bifocal, progressive) and so forth), power and type of lensmaterial (glass, plastic), specification of surface processing options(tinting, wear-resistant coating (hard coating), antireflection coating,protection against ultraviolet rays, and so forth), center thickness,edge thickness, prism, and decentration, and layout specification data(for example, the inset, and specification for the location of thesegment of a bifocal lens). Further, type of lens, and surfaceprocessing options can be substituted for by specifying at lens makerspecification, and the model name thereof.

(Preparation of Frame Date)

Next, the preparation of frame data is carried out. Frames supplied by aframe maker are stocked at a spectacles store 1, and a customer selectsa frame 4 of his/her liking. At a spectacles store, shape measurementsare taken for the selected frame thereof using an installed3-dimensional frame shape measuring apparatus (for example, GT-1000,3DFT by Hoya Corporation), and frame data (for example, shape, FPD,bridge, frame curve, rim thickness, frame material, type (full frame,rimron, rimless), and so forth) is prepared.

However, the notation method for acquisition of frame data differs foreach frame maker, and there are also various acquisition methods. Theabove-mentioned method indicated a method by which an actual frame shapeis measured, but a method, in which information is already attached to aframe beforehand as a shape data barcode tag, acquires frame data byreading the data thereof. Further, in a case in which all frame data canbe extracted from a frame model, frame data is extracted from the modeldata thereof.

Next, taking into consideration the actual shape of the head of acustomer, lens data, frame shape characteristics, and wearingconditions, the frame tilt angle is determined, and the distance betweenthe vertex of the cornea of the eye and the concave surface of a lens(VC value) is determined. A VR value is determined from the sum of thisVC value and the CR value determined above.

(Data Communications Between Spectacles Store and Lens Maker ViaPersonal Computer)

Next, data communications are carried out with a host computer at a lensmaker using a personal computer (terminal) installed at an outlet of aspectacles store. A spectacle lens ordering and inquiries system, whichis ordinarily utilized in the spectacles industry (for example, atypical system is the Hoya Online System manufactured by HoyaCorporation), can be used in the data communications thereof. To send toa host computer the various information necessary to design andmanufacture a spectacles lens required by the above-mentioned spectaclesstore, this data communications is performed using a predeterminedordering screen. FIG. 2 is the system ordering screen thereof. Variousinformation, comprising a VR value, is sent to a host computer via theordering screen.

(Design and Manufacture)

At the plant side (processing party), a host computer inputs andprocesses the various information sent from the above-mentionedterminal, and performs lens design simulation. FIG. 3 is a flowchart ofa spectacle lens manufacturing process, and is a diagram showing aprocess, comprising simulation up until the manufacture of aprescription lens thereof.

In FIG. 3, first prescribed input items are checked. In the data sentfrom the above-mentioned spectacles store, the main items thereof, whichare related to optical lens design, are physical lens data (refractiveindex, Abbe number, 1specific gravity, and so forth),prescription-related data (lens power, cylinder axis, addition,prismatic power, prism base setting, decentration, outer diameter,distance PD, near PD, lens thickness, VR value (CR value+VC value)),frame data (shape, DBL, FPD, frame curve, frame curve, and so forth),frame forward tilt, type of bevel, and other process specification data.As for lens data and frame data in particular, it is desirable toacquire basic physical and design data from a manufacturer beforehand.

And then, a spectacles wearing optical model for lens design iscomprehensively simulated from the data thereof. FIG. 4 is a schematicdiagram of an optical model of spectacles wearing, and is a diagram,which partially shows an outline of an optical model from the side. Asshown in FIG. 4, a lens is positioned in front of the eye by estimatingthe forward tilt of the frame. In this case, the VR value is the sum ofthe distance from the center of rotation R of the eye 1 to the vertex Cof the cornea 11, that is, the CR value, and the distance from thevertex of the cornea C to a reference point V on the back surface 21 ofa lens 2 (point of intersection of an extension of a straight line CRand a lens back surface 21) (VC value). In particular, if factorsaffecting the VR value, such as the improved physical constitution ofspectacles wearers in recent years, differences in the skeletalstructures of individuals, differences in the shape of the eye, and theenlargement and diversification of frames, are also added, it has beenascertained via studies that the VR value is considerably broad, and ingeneral is estimated to range from roughly 15 millimeters to around 44millimeters.

Next, optimization computations are performed by computer using lensdesign program calculations, the surface form of a concave surface,convex surface, and lens thickness are determined, and a prescriptionlens is determined. Here, for a prescription lens, options based onvariations of spectacle shape, such as an aspheric surface, sphericsurface, bifocal, progressive, refractive index, and curvature, aretaken into consideration, and either 1 type or a plurality of types ofcandidates are shown.

Furthermore, when a VC value used when measuring visual acuity differsgreatly from a VC value determined by actual measurement (a value usedin lens form design), there are cases in which it is not possible todeal with this difference via frame shape corrections (adjusting of thepads, temples, and front of a frame) and fitting adjustments (positionaladjustments at the nose, and ears). In cases such as this, since it isimpossible for the power according to visual acuity measurements toindicate the power during spectacles wearing, there are cases whencorrections become necessary. This point will be explained hereinbelow.

Ordinarily, a visual acuity examination apparatus uses a fixed VC value(hereinbelow, this value is referred to as VC0. Ordinarily, it is 14mm). Then, using this examination apparatus, an examiner (spectaclesstore, ophthalmologist, optician) obtains a corrective power value (D0).In the case of this embodiment, an examiner also takes intoconsideration frame shape, the shape of a patient's face, the correctivepower value (D0) obtained via an optometry, and type of lens, anddetermines a VC value. However, for example, more specifically, in asituation in which the eyes are set deep in the facial features of apatient, in the case of a lens with a deep minus lens back surfacecurve, the VC value is not the ordinarily used value of VC0 (14 mm), andthere are case which use as a prescription VC value a large measured VCvalue (for example, 20 mm).

In a case such as this, the corrective power value (D0) at measurementmust be corrected yet further, and a prescription lens power value (D)is calculated from the above-mentioned prescription VC value, theabove-mentioned VC0 value, and D0 value using the relational expressionhereinbelow.

D=D 0/(1+(VC−VC 0)·D 0/1000)

Further, the lens power correction quantity (ΔD) becomes

ΔD=D 0/(1+(VC−VC 0)·D 0/1000)−D 0

and when, for example, D0=−4 diopter, VC=33 mm, and VC0=27 mm, thecomputation is such that D=−0.098 diopter.

At spectacle lens design, it is desirable that the corrective powerthereof be corrected uniformly over the entire surface of a spectacle.Preferably, D is less than 0.005.

Furthermore, in this embodiment, the ordering party uses an orderingsystem, which supplies (specifies) a VC value, CR value, D value (power)and so forth to the plant side, but if this embodiment is constitutedsuch that in accordance with the ordering party transmitting initialinformation to the plant side, corrective computations are performed atthe plant side, and design lens information is returned to the orderingparty, and the ordering party references this information, preparesordering information, and sends it to the plant side once again, theburden on the ordering party can be reduced.

The basic contents performed by a lens design program will be explainedhereinbelow. The contents thereof will differ slightly in the case of asingle vision lens, and in the case of a multifocal lens. However, ineither case, the basic thinking regarding the following points is thesame.

That is, first, a lens curved surface form is initially selected as acandidate for use, and the optical characteristics of the lens thereofare determined using a ray tracing method or the like. Next, a lenscurved surface form, the curved surface of which differs in accordancewith a prescribed rule from the lens curved surface form thereof, isselected as a next candidate, and the optical characteristics of thelens thereof are determined in the same manner using a ray tracingmethod or the like. And then, the optical characteristics of both lensesare evaluated by a prescribed method, and based on the results thereof,a determination is made to either use a candidate thereof, or to offer asubsequent candidate. So-called optimization is performed by repeatingthe above process again and again until a determination is made to use acandidate lens curved surface form. Furthermore, as the VR value of aspectacles wearing optical model utilized when executing theabove-mentioned ray tracing method, a value determined for an individualis used.

The design of a single vision lens is performed as explainedhereinbelow. Since the ray tracing method itself is a well-knowntechnology, details regarding same will be omitted.

If explained based on the flowchart of FIG. 3, first, design-relateddata, comprising a VR, is treated as design input data. Based on theinput data thereof, the spectacles optical model of FIG. 4 is assumed,and ray tracing computations are carried out. In FIG. 4, the startingpoint of ray tracing is the point of rotation (R). Points for carryingout ray tracing computations are set over the entire surface of a lens2. The more numerous the number of set points, the more precise a designcan be. For example, roughly 3 to 30,000 points can be used on aspectacle lens. And then, in a state, in which a light ray of a set lenssurface location thereof is projected such that it passes through thepoint of rotation (R) thereof, and is able to pass through a spectaclelens back surface 21, that is separated by a distance VR at the opticalaxis lens center, and subsequently through a spectacle lens frontsurface 22, the optical quantity (ordinarily, astigmatism, and curvatureof field aberration) for each light ray is computed. Here, in the raytracing computation of this embodiment, the VC value and CR value, whichare related to the vertex of the cornea (C), are not used alone, butrather, the value of VR, which is the sum of the two, to used.

Here, in the case of an aspheric lens design, an aspheric lens surfaceis expressed beforehand by an expression comprising a functionalizedaspheric coefficient. A basic aspheric expression thereof is well knownin the field of optical lenses, and furthermore, based thereon, as anapplication thereof, there are well-known expressions that determinefunctionalized optical surfaces on the basis of various lens designconcepts. As specific aspheric expressions, it is possible to cite, forexample, Japanese Patent Application Laid-open No.S 52-115242, JapanesePatent Application Laid-open No. S58-24112, Japanese Patent ApplicationLaid-open No. S61-501113, Japanese Patent Application Laid-open No.S64-40926, and WO97/26578. According to these patents, a lens surfacecan be determined by determining an aspheric coefficient in a disclosedexpression.

In the present embodiment, to determine an aspheric coefficient, thatis, to determine a prescription lens in the flowchart of FIG. 3, thereis performed an optimization computation (method of least squareattenuation), which changes an aspheric coefficient in a direction thatreduces a sum of squares (called a merit function) weighted by theabove-mentioned computed optical quantity that accompanies each lightray. Then, when a merit function constitutes less than a desired setoptical quantity, an optimization computation is complete. An asphericcoefficient is determined at this point in time, and a lens form isdecided. Furthermore, the above-mentioned optical quantities are cleareven from the optical model of FIG. 4, but these optical quantities arenot individually functionally dependent on a VC value, and a CR value,which are 2 elements of a VR value, but rather have a functionalrelation to a VR value, which is the sum of a VC value and a CR value.

FIG. 5 is a diagram showing optical data of a prescription lens with aVR value of 27 mm, which was determined by the above-mentioned designtechnique. The basic specification for this prescription lens is aprescription for myopia, and is a single vision aspheric plastic lens(diethylene glycol bis allyl carbonate) of lens power: −4.00 diopter(D), refractive index (nd): 1.50, and outside diameter: 70 mm.

FIG. 6 is a diagram showing performance data of a case in which a personwith a VR value of 27 mm wore a prescription lens with a VR value of 27mm (Refer to FIG. 5). As shown in FIG. 6, there is practically no powererror (average power error) in any angle of visual line, and it isevident that a lens design, which strives for optimization in an averagepower, has been performed, and that this lens design has extremelyoutstanding performance.

FIG. 7 is a diagram showing performance data of a case in which a personwith a VR value of 33 mm wore a prescription lens with a VR value of 27mm (Refer to FIG. 5) (Target distance was set at infinity. Same holdstrue hereinbelow). As shown in FIG. 7, it turns out that large powererrors (average power errors) are generated by the angle of visual line.That is, it turns out that power errors occur when a angle of visualline moves to a side field of view, which is away from the center of thelens, for example, in a direction of 30 degrees or 35 degrees. Thequantity thereof is 0.245 (D) at 35 degrees, and, as can be seen, isextremely large. For a spectacle lens, dioptric power classification isgenerally done at a pitch of 0.25 (D), and the power error value thereofis not a quantity that can be tolerated, indicating the need to selectanother prescription lens. Because all spectacle lenses ordinarily usethe same design for a single lens item, the case shown in FIG. 7 can bethought of as a model case that occurs on a daily basis.

FIG. 8 is a diagram showing optical data of a prescription lens with aVR value of 33 mm. Compared to the optical data of a prescription lenswith a VR value of 27 mm (Refer to FIG. 5), the difference in convexsurface curve values is 0.0 diopter at a distance from the opticalcenter of 0.0 mm, and constitutes a −0.184 diopter at 15 mm. Becausethis is an aspheric lens design, unlike a spheric lens design, anonuniform convex curve correction is performed along the lens radial,and this differs from a uniform curve correction of power correctionprocessing.

FIG. 9 is a diagram showing performance data of a case in which a personwith a VR value of 33 mm wore a prescription lens with a VR value of 33mm (Refer to FIG. 8). As shown in FIG. 9, there is practically no powererror (average power error) in any angle of visual line, and it isevident that a lens design, which strives for optimization in an averagepower, has been performed, and that this lens design has extremelyoutstanding performance.

FIG. 10 is a diagram showing optical data of a prescription lens with aVR value of 27 mm in a case in which the power is a prescription forhyperopia, and is +4.00 (D), FIG. 11 is a diagram showing performancedata of a case in which a person with a VR value of 27 mm wore aprescription lens with a VR value of 27 mm (Refer to FIG. 10) (Targetdistance is set at infinity. The same holds true for hereinbelow), FIG.12 is a diagram showing performance data of a case in which a personwith a VR value of 33 mm wore a prescription lens with a VR value of 27mm (Refer to FIG. 10), FIG. 13 is a diagram showing optical data of aprescription lens with a VR value of 33 mm in a case in which power is+4.00 (D), and FIG. 14 is a diagram showing performance data of a casein which a person with a VR value of 33 mm wore a prescription lens witha VR value of 33 mm (Refer to FIG. 13). It is evident that the examplesshown in these figures achieved the same results as the case shown inFIG. 5-FIG. 9.

FIG. 15 is a table for determining and showing power errors for variouscombinations of convex surface curve (base curve) values and lens powervalues in a case in which there is a single vision lens, and the VRvalue is set at 27 mm, and FIG. 16 is a graph for showing therelationships indicated in FIG. 15 as power error contour lines.Furthermore, the examples shown in these figures are examples that treatthe visual line direction as a 30 degree direction. Further, in FIG. 16,the vertical axis is convex surface curves (base curves), and thehorizontal axis is lens powers. From this table, it is clear that if aperson with a lens power of −6.00 (D) selects a base curve of 2 (D), hewill be able to achieve a lens with a good design that has a small powererror.

FIG. 17 is a table for determining and showing power errors for variouscombinations of convex surface curve (base curve) values and lens powervalues in a case in which there is a single vision lens, and the VRvalue is set at 33 mm, and FIG. 18 is a graph for showing therelationships indicated in FIG. 17 as power error contour lines. Theexamples shown in these figures are examples that treat the visual linedirection as a 30 degree direction. Further, in FIG. 18, the verticalaxis is convex surface curves (base curves), and the horizontal axis islens powers. From this table, it is clear that if a person with a lenspower of −6.00 (D) selects a base curve of 1 (D), he will be able toachieve a lens with a good design that has a small power error.

From the above-mentioned results, it is clear that, compared to a casein which the VR value is 27 mm, when the VR value constitutes 33 mm,there is need for a lens with a power that is higher by −0.098 diopter.That is, in the above-mentioned examples, when the VR value changes from27 mm to 33 mm, a lens that has strong power in terms of an absolutevalue is needed. The power correction value under the same conditions asmentioned above is a −0.098 diopter, that is, a −4 diopter (27 mm) lensis corrected, and must become a −4.098 diopter (33 mm) lens. Conversely,with regard to lens curve, when the VR changes from 27 mm to 33 mm,looking at the pertinent places in FIG. 15, and FIG. 17, it can be seenthat a curve, which has practically no aberration at a D=−4 diopter is aroughly 3.3 curve for VR−27 mm, and is a roughly 2.3 curve for VR=33 mm.That is, in accordance with the difference in VR, the lens curveundergoes bending, and a roughly 1 curve shallower curve is used. Theeffects of using a VR value, and performing lens design can berecognized here as well. Furthermore, in a case in which a single-visionspectacles exclusively for near use is required for the purpose of nearwork, it is desirable, of course, to use a near PD, and to use a near VRvalue.

Next, a case of a progressive-power lens will be explained. The designof a progressive-power lens is basically the same as that for a singlevision lens, but from the standpoint of the structure thereof, there arealso points that differ. Hereinbelow, the importance of a method fordetermining (correcting) the inset of a layout for a near portion willbe explained while referring to FIG. 19 through FIG. 25.

A progressive-power lens is constituted from a distance portion for longdistance vision, a near portion for short distance vision, and anintermediate portion for intermediate vision, which smoothly connectsthe distance portion and the near portion. From the standpoint of lensdesign, a spheric design is generally used for the distance portion andnear portion (but there are also aspheric designs), and an asphericdesign is used for the intermediate portion. Therefore, from thestandpoint of design, it can be said that a progressive-power lens has asurface, which combines the spheric design of the above-mentioned singlevision lens with an aspheric design.

Further, since a progressive-power lens is a lens for presbyopia, theportion from the intermediate portion to the near portion receives themost noticeable affects resulting from a difference in VR, and in thisembodiment, the layout state thereof will be explained by focusing onthe near portion thereof.

First, the aspect of designing a progressive-power lens, whichconstitutes the basis for this embodiment, will be explained.Furthermore, since the designs for a progressive refracting surfaceitself are diverse, and various are capable of being used, in thisembodiment, the basic structural portion will be explained.

The progressive-power lens of this embodiment is constituted such thatlens is designed based on a prescribed optical design concept, the basicprogressive retracting surface thereof is set as a functionalizedsurface via a prescribed numerical expression in a lens design program,and a prescription lens surface can be set up by inputting prescribedform determining element parameters, such as prescribed dioptric power.(Since lens design systems, which express a lens surface as afunctionalized surface, and make use of programmed computers, havebecome well-known in recent years in particular (for example,WO98/16862), in this embodiment, a detailed explanation in particular ofthe design methods thereof will be omitted.)

Further, for the basic progressive refracting surface thereof, a lenssurface is set up by determining the power distribution across an entirelens surface of a distance portion, a intermediate portion, and a nearportion. And then, as elements for determining the power distributionthereof, there are the base curve value of a distance portion, addition,horizontal power distribution of a distance portion and a near portion,the layout of a distance portion, near portion, and intermediateportion, progressive zone power change distribution, positioning ofeither a principal meridian or a principal sight line, positioning ofastigmatism distribution, and positioning of average power distribution.And then, a prescribed progressive refracting surface is set up byadding weighting to, and changing the weighting of these elements inaccordance with individual design concepts. As precedents for the designthereof, it is possible to cite specifically, for example, JapanesePatent Application Laid-open No. S57-210320, Japanese Patent ApplicationLaid-open No. H8-286156, and Japanese Patent Application Laid-open No.H9-90291, which are related to applications of the applicants of thiscase.

And then, a progressive-power lens created based on a certain prescribeddesign concept like this, a basic progressive refracting surface,comprising a plurality of base curves (for example, 2-8 curves) inaccordance with the prescribed dioptric power thereof, is preparedbeforehand. And a standard near portion inset INSET0 is set as aninitial value (for example, 2.5 mm) in each.

The near portion inset thereof is an inset toward the inner side of thenear portion, which is set on a basic progressive refracting surface bytreating as a reference a passage point on front surface of the lens ofa line of sight at distance forward viewing (for example, a point on theprincipal meridian of a progressive-power lens), and is the distance inthe horizontal direction from the principal meridian to the center ofnear portion of a progressive-power lens (Refer to FIG. 25).

From among the above-mentioned plurality of base curves, a basicprogressive refracting surface of a prescribed base curve thatcorresponds to the prescribed dioptric power (for example, a 7 curve inthe case of ADD 2.00 with a SPH +3.00 diopter) is selected, and aninitial value of INSET0 is set in the near portion of the basicprogressive refracting surface thereof.

Next, this basic progressive refracting surface is treated as a frontsurface, and a lens design program is used to determine the form andlocation (a relative location on the optical axis relative to the frontsurface) of a back surface of the lens, such that the lens thereofsatisfies the power as prescribed (comprising a prism in a case in whicha prism prescription is necessary).

Preferably, a back surface of the lens to set at this time, such thatthe thickness of the lens thereof is made thinnest owing to frame shape,type of frame, and layout of lens relative to frame. Because methods fordetermining a back surface of the lens having an optimal thickness likethis are being implemented in the spectacles industry in lens orderingsystem thereof, and are well-known technologies (for example, JapanesePatent Application Laid-open No. S59-55411, the HOYA METS system, and soforth), an explanation thereof will be omitted for this embodiment.

Next, since the form and location of both a convex surface and a concavesurface of the lens, which constitutes a reference, are determined, aray tracing method is used on the lens thereof, and the location of thenear portion is determined.

In this case, as shown in FIG. 3, to accurately determined the inset ofthe near portion, a provisional optical model of a wearing state is setup on the basis of a prescribed near side object distance (workingdistance for near vision: a target distance for work to be done at ashort distance) and the locations of the right and left eyes, a VRnumber of the invention of this case, which is obtained by measuringeach individual spectacles wearer, distance PD, frame data, and frameforward tilt, and ray tracing computations are performed.

That is, the location of a point at which the visual line passes throughthe front surface of the lens when the right and left eyes actuallyidentify a near object is determined via simulations based on theabove-mentioned optical model, and next, a horizontal directionconstituent (INSET1: the horizontal distance from the principal meridianto the center of near portion of the lens), which is the inset whenthere is convergence from the visual line in distance vision to thevisual line in near vision in the location thereof, is determined.

Next, a determination is made as to whether or not the initial insetvalue INSET0, which was set in the basic progressive refracting surface,is identical to the first inset INSET1, which was determined here. WhenINSET0 and INSET1 are not identical, the value of INSET0, which wasprovided as an initial value, is replaced by the value of INSET1. Andthen, as shown in the flowchart of FIG. 19, the newly replaced inset(INSET1) to reset once again in the near portion of the basicprogressive refracting surface, simulation is performed for the newprogressive surface, for which the near portion optical layout haschanged, and the above-mentioned processing is repeated.

In general, an inset is rarely determined by the initial ray tracing.This is because an optical model is changed by a change in the VR value,and the visual line location on a lens in a spectacles wearing state,and the visual line location on a lens when looking at a near object inaccordance with a prescription power and prism change greatly. FIG. 24is a diagram illustrating the divergence of the visual line betweenINSET0 and INSET1. This divergence is due to the fact that a line ofsight passing through a lens on its way toward a near object isrefracted by the lens, and the visual line actually passes through alocation that differs from INSET0, which was set as a standard inset.

That is, the optical layout of the near portion changes in accordancewith the changing of the inset, and to deal with this, the intermediateportion and distance portion are also changed, and a new progressiverefracting surface is created while maintaining the basic refractiondesign surface, and then, an ideal inset is sought, and optimization isperformed until optical conditions are satisfied such that the visualline in near vision is able to pass through a prescribed near objectdistance. Then, when INSET (n−1)=INSET (n), the repetitive processingthereof (optimization) is completed, and a progressive refractingsurface and back surface of the lens are determined as the finalprescription lens.

Especially in a case in which ray tracing is performed on a lenscomprising a plurality of surface forms like a progressive refractingsurface, it is necessary to determine a correct inset by repetitiveprocessing like this so that INSET (n−1)=INSET (n) can be achieved.Next, an example in which the above-mentioned inset optimization isimplemented will be explained based on the figures.

FIG. 20-1, FIG. 20-2, and FIG. 20-3 are design examples of progressiverefracting surfaces of progressive-power lenses with addition 2.00 D,when, as a condition, VR=27.0 mm is provided as a standard value.

At this time, the refractive index of a lens material is 1.596, thelength of the progressive zone from the distance portion to the nearportion is 15 mm, and progressive refracting power increases, having alocation 4 mm upwards from the center as a base point, and achievesaddition 2.00 D at a location 11 mm downward from the center. The PD ofthe right and left eye is 32.0 mm in both the right and left, and thenear object distance is set at 33.3 cm.

Each diagram is a distribution of surface astigmatism, and surfaceaverage power for each progressive refracting surface, and shows adistribution range of φ80 mm. Further, a φ50 mm auxiliary circle isplaced on the inside portion.

FIG. 20-1 is a progressive refracting surface form for which thedistance power (DF) for both the right and left is set at +3.00D, theconvex curve (ABC) is set at 5.94D, lens thickness at the geometriccenter is set at 5.1 mm, and the prism at the geometric center is set at1.0Δ base 270°, FIG. 20-2 is a progressive refracting surface form forwhich the distance power (DF) for both the right and left is set at0.00D, the convex curve (ABC) is set at 4.72D, center thickness is setat 2.7 mm, and the prism is set at 1.0Δ base 270°, and FIG. 20-3 is aprogressive refracting surface form for which the distance power (DF)for both the right and left is set at −3.00D, the convex curve (ABC) isset at 3.49D, center thickness is set at 1.5 mm, and the prism is set at1.0Δ base 270°.

Looking at the distributions of astigmatism and average power in thevicinity of the near portions of these FIG. 20-1, FIG. 20-2, and FIG.20-3, it is clear that the positioning of a near portion changes inaccordance with differences in distance power (DF). In accordance withdifferences of −3.00D, 0.00D, +3.00D in distance power (DF), the insetsof the near portions sequentially steadily increase. This difference isbecause the prism effects of the near portions of progressive-powerlenses differ mainly due to differences in distance power (DF).

FIG. 21-1, FIG. 21-2, and FIG. 21-3 are design examples of when only theVR value of the design examples of FIG. 20 is treated as a value that islarger than the standard value, and is given as VR=33.0 mm.

FIG. 21-1 is a progressive refracting surface form for which thedistance power (DF) for both the right and left is set at +3.00D, theconvex curve (ABC) is set at 5.94D, center thickness is set at 5.1 mm,and the prism is set at 1.0Δ base 270°, FIG. 21-2 is a progressiverefracting surface form for which the distance power (DF) for both theright and left is set at 0.00D, the convex curve (ABC) is set at 4.72D,center thickness is set at 2.7 mm, and the prism is set at 1.0Δ base270°, and FIG. 21-3 is a progressive refracting surface form for whichthe distance power (DF) for both the right and left is set at −3.00D,the convex curve (ABC) is set at 3.49D, center thickness is set at 1.5mm, and the prism is set at 1.0Δ base 270°.

In the case of these FIG. 21-1, FIG. 21-2, and FIG. 21-3 as well, thesame as the case of FIG. 20, the positioning of a near portion changesin accordance with differences in the distance power (DF), but it isclear that the insets of the near portions are larger in the case ofFIG. 21 than the case of FIG. 20 for all the distance power s (DE). Thisdifference is because the location at which the visual line passesthrough a progressive-power lens when looking at a near object differsgreatly according to differences in VR in addition to differences indistance power (DF).

FIG. 22-1, FIG. 22-2, and FIG. 22-3 are design examples of when only theVR value of the design examples of FIG. 20 is treated as a value that issmaller than the standard value, and is given as VR=20.0 mm.

FIG. 22-1 is a progressive refracting surface form for which thedistance power (DP) for both the right and left is set at +3.00D, theconvex curve (ABC) is set at 5.94D, center thickness is set at 5.1 mm,and the prism is set at 1.0Δ base 270°, FIG. 22-2 is a progressiverefracting surface form for which the distance power (DF) for both theright and left to set at 0.00D, the convex curve (ABC) is set at 4.72D,center thickness is set at 2.7 mm, and the prism is set at 1.0Δ base270°, and FIG. 22-3 is a progressive refracting surface form for whichthe distance power (DF) for both the right and left is set at −3.00D,the convex curve (ABC) to set at 3.49D, center thickness is set at 1.5mm, and the prism is set at 1.0Δ base 270°.

In the case of these FIG. 22-1, FIG. 22-2, and FIG. 22-3 as well, thesame as the cases of FIG. 20 and FIG. 21, the positioning of a nearportion changes in accordance with differences in the distance power(DF), but it is clear that the insets of the near portions are smallerin the case of FIG. 22 than the case of FIG. 20 for all the distancepower s (DF), and compared to FIG. 21, the insets of FIG. 22 areextremely smaller. This difference, too, is because the location atwhich the visual line passes through a progressive-power lens whenlooking at a near side object differs greatly according to differencesin VR in addition to differences in distance power (DF) the same as thecase of FIG. 21.

FIG. 23 shows the results of calculating as specific numerals the nearportion insets INSET provided to the respective determined progressiverefracting surfaces shown in FIG. 20, FIG. 21, and FIG. 22. From this itis clear that the insets of the near portions change in accordance withdifferences in VR.

It is desirable for this to be performed in accordance with the lensesof the left and right eyes. Further, this method can also be used in thesame way in a case in which the optical layout of the near portion of abifocal (segment height, left-right location, and so forth) isdetermined, and a prescription lens is determined. That is, as shown inFIG. 26, since the near segment portion of a bifocal layout block ispartitioned by a boundary line, the location of the near portion isadjusted in the same manner as the above-mentioned example of aprogressive-power lens.

Further, in addition to an inset of a near portion, astigmatism, averagepower error, and distortion can also be determined from ray tracing foreither a selected basic progressive refracting surface, or a correctedprogressive refracting surface and a back surface of the lens in theflowchart of FIG. 19.

Thus, when optimizing the inset of a near portion, the form of aprogressive refracting surface can be corrected, and aberrationcorrection can be performed simultaneously from such values asastigmatism, average power error, and distortion determined by raytracing.

In correcting the aberration of a progressive refracting surface byoptimization, optimization is performed beforehand for a basicprogressive refracting surface so as to diminish the respectivedeviations (ΔA1, ΔB1, ΔC1) between estimated astigmatism A0, averagepower distribution B0 and distortion C0, and astigmatism A1, averagepower distribution B1 and distortion C1 determined by ray tracing.Weighting, which corresponds to a location on a basic progressiverefracting surface (center area, lateral area, distance portion, nearportion, and so forth), is performed for each of the deviations thereofat this time. At this time, ray tracing is performed, and optimizationis performed in the respective areas by using in the distance portion aVR value that differs at distance vision and at near vision.Furthermore, for the intermediate portion, two VR values areinterpolated and used at distance vision and near vision in accordancewith a localized additional refracting power in the location thereof.

Further, depending on the lens design, it is also possible to use apartial VR value for either only a distance portion, or only a nearportion.

The results thereof are displayed using, for example, an astigmatismdiagram, bird's-eye view, and so forth, by a display processing programfor optical performance computation results provided in a lens designprogram, and are constituted so as to enable comparison and study.Further, such results are set up to also be displayable on the personalcomputer of the ordering party via a communications line. The spectaclesstore side either confirms or selects a desired lens based on suchresults. Naturally, wearing parameters can be changed, new wearingconditions can be set, and a new prescription lens can be determinedbased on the simulation data thereof.

As for the results thereof, there is performed, based on information ofeach type sent to a host computer by a display processing program foroptical performance computation results provided in a lens designprogram, computations to determine how a spectacle lens of theindividual design that is being ordered differs from a standardspectacle lens, the results thereof are returned to a spectacle storeside terminal apparatus, and the differences therebetween can also bedisplayed thereon. A standard lens to be used as a comparison object canalso be specified by the spectacles store side at this time, and in acase in which there is no specification of a standard lens as acomparison object, this embodiment is constituted such that a lens setin the host computer beforehand is treated as the comparison object.Based on such results, the spectacles store side can check thedifferences between a desired individual designed lens and a standardlens.

A number of methods can be cited for comparing the differences between aspectacle lens of an individual design, and a standard spectacle lens.One method is a method in which the kind of aberration distributionachieved when the end user puts on the spectacles thereof is determinedby ray tracing, and the results thereof are displayed on the spectaclesstore side terminal apparatus by lining up the aberration distributionof the standard spectacles beside the aberration distribution of theindividually designed spectacles.

For example, if it is a single-vision aspheric lens, there is a method,which displays the power error and astigmatism of each angle of visualline to the lens concave surface. Even in the case of aprogressive-power lens, there is a method, which displays as theaberration distribution of an entire lens surface via contour lines thedistribution of astigmatism and average power of each angle of visualline toward the lens concave surface.

Further, as a simplified comparison method, there is a method such asthe following. There is a method, which, in the case of a single-visionaspheric lens, compares and displays using numerals and graphs a powererror and astigmatism of when there is a 30 degree angle of visual linetoward the lens concave surface, and the lens convex surface curve atthe design center location of a spectacle lens of an individual design,and a standard spectacle lens, respectively. For a progressive lens,too, there is a method, which compares and displays using numerals andgraphs astigmatism and average power in the 8 directions of upwards,downwards, inwards, outwards, diagonally inwards upwards, diagonallyoutwards upwards, diagonally inwards downwards, and diagonally outwardsdownwards at a 30 degree angle of visual line toward a lens concavesurface, and a lens convex surface curve in the respective design centerlocations. Furthermore, it is desirable that price, delivery time andother such information also be included.

(Lens Manufacturing)

Next, when order receipt of the above-mentioned prescription lens isdetermined by an order, the processing data thereof is prepared. Thisprocessing data is prepared on the basis of a lens processing program.Processing conditions of processing equipment are determined, driving ofprocessing equipment is controlled, and instructions are given forselecting processing tools and for selecting a lens material byprocessing data. This processing data are sent to each manufacturingequipment in a factory with processing instructions.

And then, at the manufacturing site, a lens blank is selected based onthe processing instructions, and cutting and grinding lens processingare performed using an NC cutting machine. Also in a case in whichsurface processing (formation of a wear-resistant hard coating,formation of an anti-reflection coating, lens tinting, water repellantprocessing, formation of an ultraviolet ray cutting coating,anti-fogging treatment, and so forth) is required, processing isperformed here. Then, a round shaped prescription lens is completed.Further, at this point, there are also cases in which a lens can beselected from finished products stocked beforehand for lens manufacture.

Next, the above-mentioned round lens is made to correspond to aprescribed lens form, and a bevel (V-shaped edge) is formed at the edgebased on spectacles layout information. The formation of the bevel isperformed by a machining center. This processing is performed using atool and processing method disclosed in Japanese Utility ModelApplication Laid-open No. H6-17853, and Japanese Patent ApplicationLaid-open No. H6-34923, which are related to the above application ofthis applicant. Here, too, selecting of type of lens material (glass,plastic, polycarbonate, acrylic, and so forth), selecting of framematerial, inputting of frame PD (FPD, DBL), inputting of PD (both eyes,one eye), inputting of horizontal decentration distance X, inputting ofvertical decentration distance Y, inputting of astigmatism axis,inputting of finished size, and specifications of bevel shape are usedas processing conditions, and when the processing equipment is set tothe processing mode, the input data thereof is automatically introducedby a program.

And then, when these prescribed items are set, and the start switch ispressed, edge planing and bevel formation are automatically performed atthe same time. A bevel formed lens is manufactured in this manner,passes through an inspection process at the factory, and is shipped to aspectacles store. At the spectacles store, the bevel formed lens isfitted into a selected frame, and spectacles are assembled. Further, inthis embodiment, the bevel formation was explained as an aspect, whichis implemented by a manufacturer, but this can also be performed at aspectacles store, and is not particularly limited to the manufacturingflow of this embodiment.

Based on the above-mentioned results, good spectacles can be obtained byselecting an appropriate base in accordance with a VR value.Furthermore, with regard to a lens optical performance evaluation index,average power was utilized in the above-mentioned aspect of theembodiment, but it is not limited thereto. There are indices such asastigmatism, average power error, distortion, spectacles magnification,RMS, and combinations thereof, and the index is not particularlylimited. Further, a lens design program, inquiry-based simulationprogram, display program and so forth can be incorporated beforehandinto an ordering party terminal and accessory equipment (CD or thelike), and can also be run on the same personal computer in the sense ofan apparatus having a kind of information processing function.

As explained hereinabove, the present invention makes it possible todesign and manufacture a higher performance spectacle lens that accordswith the VR value (VC+CR) of each individual person by determining, bymeasuring each individual spectacles wearer, a value for the distance VRfrom a reference point on the back surface of a spectacle lens to thecenter of rotation of the eye, which adds a value for the distance VCfrom a reference point on the back surface of a spectacle lens whenspectacles are being worn to the vertex of the cornea of a spectacleswearer's eyeball, which is one of the required data in spectacle lensdesign, and a value for the distance CR from the above-mentioned corneavertex to the center of rotation of the eye, using the value thereof toperform spectacle lens design, and to manufacture a spectacle lens onthe basis of the design specifications thereof.

As explained hereinabove, this spectacle lens and manufacturing methodtherefor makes it possible to supply a spectacle lens that excels infeeling when wearing it by designing and manufacturing a spectacle lenstaking into consideration the distance between the center of rotation ofthe eye and the spectacle lens for an individual spectacles wearer, andcan be applied to any of a single vision lens, a multifocal lens, and aprogressive-power lens.

What is claimed is:
 1. A spectacle lens, wherein there is determined, byeither measurement or specification for an individual spectacles wearer,a value of the distance VR from a reference point on the back surface ofa spectacle lens to the center of rotation of the eye, which is given byadding a value of the distance VC from a reference point on the backsurface of a spectacle lens to the vertex of the cornea of the eye of aspectacles wearer when spectacles are being worn, which is one of therequired data in spectacle lens design, and the distance CR from saidcornea vertex to the center of rotation of the eye, which is calculatedby measuring the axial length CO of the eye of a spectacles wearer andusing a value obtained based on measurement data thereof, and thespectacle lens is designed using the value VR thereof, and ismanufactured based on the design specifications.
 2. A spectacle lens,wherein a value of the distance VR from a reference point on the backsurface of a spectacle lens to the center of rotation of the eye, whichis given by adding a value of the distance VC from a reference point onthe back surface of a spectacle lens to the vertex of the cornea of theeye of a spectacles wearer when spectacles are being worn, which is oneof the required data in spectacle lens design, and the distance CR fromsaid cornea vertex to the center of rotation of the eye, is determinedfor distance vision, near vision, specified distance vision, andcombination thereof, respectively, and the value of the distance VR iseither selected and used on the basis of lens optical characteristics,or used for appropriate viewing areas of a spectacle lens, respectively,and the spectacle lens is designed for an individual spectacles wearerusing the value thereof and is manufactured based on the designspecifications.
 3. A spectacle lens, wherein processing is performed byobtaining an optimized lens form based on design and/or processingcondition data information selected as needed from among informationcomprising a prescription value, which comprises spectacle lensinformation, spectacle frame information, the VR value which is thedistance from a reference point on the back surface of a spectacle lensto the center of rotation of the eye of an individual spectacles wearer,and related data on an amount of inset for near vision determined basedon said VR value, layout information, and processing specificationinformation.
 4. The spectacle lens according to claim 3, wherein a basecurve of a convex surface is determined based on said VR value.
 5. Thespectacle lens according to claim 3, wherein power error correction isperformed for a pre-set reference prescription surface based on said VRvalue.
 6. A spectacle lens manufacturing method, wherein a terminalapparatus, which is installed at a spectacle lens ordering party side,and an information processing system, which is installed at a spectaclelens processing party side and is connected by a telecommunications lineto said terminal apparatus are provided for designing and manufacturinga spectacle lens based on information sent to said informationprocessing system via said ordering party terminal apparatus, the methodcomprising the steps of: sending to said information processing systemvia said terminal apparatus design and/or processing condition datainformation selected as needed from among information comprising aprescription value, which comprises spectacle lens information,spectacle frame information, and data related to the VR value which isthe distance from a reference point on the back surface of a spectaclelens to the center of rotation of the eye of each spectacles wearer,layout information, and process specification information; and obtainingan optimized lens form based on said information sent by saidinformation processing system, determining processing conditions, andmanufacturing a spectacle lens.
 7. A spectacle lens manufacturingmethod, wherein a terminal apparatus, which is installed at a spectaclelens ordering party side, and an information processing system, which isinstalled at a spectacle lens processing party side and is connected bya telecommunications line to said terminal apparatus are provided fordesigning and manufacturing a spectacle lens based on information sentto said information processing system via said ordering party terminalapparatus, the method comprising the steps of: sending to saidinformation processing system via said terminal apparatus design and/orprocessing condition data information selected as needed from amonginformation comprising a prescription value, which comprises spectaclelens information, spectacle frame information, and data related to theVR value which is the distance from a reference point on the backsurface of a spectacle lens to the center of rotation of the eye of eachspectacles wearer, layout information, and process specificationinformation; determining an optimized lens form based on saidinformation sent by said information processing system; also determininga standardized lens form by said information processing system using astandardized VR value in place of said VR value obtained for eachspectacles wearer, while using other design and/or processing conditiondata sent via said terminal; and comparing the optical characteristicsof said optimized lens form with the optical characteristics of saidstandardized lens form, and based on the results of the comparison,selecting either one of said lens forms, determining processingconditions of this selected lens form, and manufacturing a spectaclelens.
 8. A spectacle lens manufacturing method, wherein a spectacle lensis designed and manufactured while information is exchanged between aterminal apparatus, which is installed at a spectacle lens orderingparty side, and a manufacturing side computer, which is connected to theordering side computer to enable information exchange; the methodcomprising the steps of: inputting via said terminal apparatus designand/or processing condition data information selected as needed fromamong information comprising a prescription value, which comprisesspectacle lens information, spectacle frame information, and datarelated to the VR value of a spectacles wearer, layout information, andprocess specification information, and obtaining an optimized lens formbased on an optical model of wearing conditions simulated on the basisof the inputted information, determining processing conditions, andmanufacturing a spectacle lens.
 9. The spectacle lens according to claim1, wherein said center of rotation of eye is determined for distancevision, near vision, specified distance vision, and combination thereof,respectively, and is either selected and used on the basis of lensoptical characteristics, or is used for appropriate viewing areas of aspectacle lens, respectively.